[EuiFilePicker] Fix can still be cleared when disabled (#5603)

* Pass disabled prop down to buttons in EuiFilePicker

* Add EuiFilePicker bugfix to changelog

* Don't display remove buttons at all when EuiFilePicker is disabled

CHANGELOG.md

@@ -5,6 +5,7 @@
 **Bug fixes**
 
 - Fixed `EuiInMemoryTable`'s `onTableChange` callback not returning the correct `sort.field` value on pagination ([#5588](https://github.com/elastic/eui/pull/5588))
+- Fixed `EuiFilePicker` allowing files to be removed when `disabled` ([#5603](https://github.com/elastic/eui/pull/5603))
 
 ## [`46.2.0`](https://github.com/elastic/eui/tree/v46.2.0)
 

src/components/form/file_picker/file_picker.tsx

@@ -175,7 +175,7 @@ export class EuiFilePicker extends Component<EuiFilePickerProps> {
             clearButton = (
               <EuiLoadingSpinner className="euiFilePicker__loadingSpinner" />
             );
-          } else if (isOverridingInitialPrompt) {
+          } else if (isOverridingInitialPrompt && !disabled) {
             if (normalFormControl) {
               clearButton = (
                 <button